1. Field of the Invention
The invention relates to machines for plastic injection molding and more particularly to nozzles mounted in the molds of such machines which have internal heaters which maintain the plastic at the discharge end of the nozzle in a plasticized condition.
2. Description of the Prior Art
Gilmore Pat. No. 3,010,155 and Seres Pat. No. 3,707,265 show nozzles of this general type. The nozzles are supplied with the molten plastic either by a manifold or a machine nozzle having a spherical tip. The conventional nozzle has passageway means from its rearward end to the tip or discharge end, this means being formed between an inner shank and an outer body, the heater being disposed within the shank. The shank in this conventional construction is integral with a shank housing carried by the mold. A tapered spreader member is silver-soldered to the forward end of the shank to form the annular converging passage leading to the discharge orifice of the nozzle.
If it is required in such a conventional nozzle to replace the heater, it is necessary to first remove the entire nozzle from the mold, then remove the outer body from the shank housing, and melt the silver-solder so that the spreader member may be removed from the shank. After the spreader member is removed, there will be access to the heater which is extracted from the forward end of the shank. This is a time consuming and expensive process.
Another disadvantage of the conventional nozzle as exemplified by the above mentioned patents, is the fact that each nozzle will only be usable in a certain size of mold. Since most molds differ in size, it has been necessary in the past for the manufacturer to stock many different sizes of nozzles so that they could be mounted in the different molds.